Indoor unit for air conditioning apparatus

ABSTRACT

An indoor unit for an air conditioning apparatus is provided. The indoor unit includes a cross flow fan having a structure that can reduce noise and flow resistance of air passing through a heat exchanger in the indoor unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This claims the priority to Korean Patent Application No.10-2008-0117860 (filed in Korea on Nov. 26, 2008), the entirety of whichis incorporated herein by reference.

BACKGROUND

1. Field

An air conditioning system is provided, and in particular an indoor unitfor an air conditioning system is provided.

2. Background

In general, an air conditioning apparatus cools/heats a room using acompressor, a condenser, an expander, and an evaporator. The airconditioning apparatus may be a separated-type air conditioningapparatus in which an indoor unit is separated from an outdoor unit, oran integrated-type air conditioner in which an indoor unit is integratedwith an outdoor unit. Improvements in efficiency, effectiveness andnoise level during operation are desirable in either type of airconditioning apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements, wherein:

FIG. 1 is a side cross-sectional view of a structure of an indoor unitfor an air conditioning apparatus according to an embodiment as broadlydescribed herein;

FIG. 2 is a front perspective view of a chassis of the indoor unit shownin FIG. 1;

FIG. 3 is a partial perspective view of a fan of the indoor unit shownin FIG. 1;

FIG. 4 is a side view of the fan shown in FIG. 3;

FIG. 5 is a perspective view of a blade corresponding to a portion A ofFIG. 4;

FIG. 6 is a graph of a relationship between an outer circumferentialangle and noise in a fan of an indoor unit according to an embodiment asbroadly described herein;

FIG. 7 is a graph of a relationship between a ratio of inner diameter toouter diameter and noise in a fan of an indoor unit according to anembodiment as broadly described herein;

FIG. 8 is a graph of a relationship between a ratio of thickness tolength of a fan and noise in a fan of an indoor unit according to anembodiment as broadly described herein;

FIG. 9 is a graph of a relationship between a ratio of an insertiondepth to length of a fan and noise in a fan of an indoor unit accordingto an embodiment as broadly described herein; and

FIG. 10 is a graph of noise performance improvement of an indoor unitincluding a fan and an indoor unit as embodied and broadly describedherein.

DETAILED DESCRIPTION

In a separated air conditioning apparatus, a fan and a heat exchangerthat performs a heat exchange operation with indoor air drawn in by thefan may be received in the indoor unit. Air may flow from, for example,a front upper surface of the indoor unit downward to be discharged at alower portion of the front surface of the indoor unit. A high efficiencycross flow fan may be installed in an indoor unit that is installed on awall surface to reduce power consumption.

A heat exchanger that has an increased heat exchange area may also beused to improve efficiency. Such a heat exchanger may include coolantpipes arranged in 3 rows forward and backward. However, if this type of3 row heat exchanger is used in an indoor unit in combination with across flow fan, system resistance may be increased. As system resistanceis increased, the noise level at a given air flow rate may also beincreased. For example, a surging noise may be generated. A structure inwhich the fan may be operated at a desired level without generatingabnormal noise would be beneficial, especially when air resistance isincreased due to dust accumulated on a heat exchanger or a filter afterextended use, and a 3 row heat exchanger and cross flow fan are used.

FIG. 1 is a side cross-sectional view of an indoor unit 10 for an airconditioning apparatus, including a chassis 11 that may be closelyadhered to a support surface, such as, for example, a wall, a frontframe 12 that is coupled to a front side of the chassis 11, a frontpanel 13 that is rotatably or slidably provided on a front surface ofthe front frame 12, a fan 17 that is received in a space formed by thechassis 11 and the front frame 12 to draw indoor air into the indoorunit 10, and a heat exchanger 16 that surrounds the fan 17 to perform aheat exchange operation with the indoor air.

A stabilizer 112 may be provided on a front surface of the chassis 11 toallow air flow to be generated as the fan 17 rotates. A heat exchangerseating part 111 that supports a first end of the heat exchanger 16 maybe formed on an upper side of the stabilizer 112. An inlet grill 121 maybe formed on an upper surface of the front frame 12 to guide the flow ofindoor air into the indoor unit 10, and a front surface inlet port 122may be formed on a front surface of the front frame 12. A filter 15 maybe mounted on a front surface of the heat exchanger 16 to filter indoorair drawn in through the inlet grill 121 and the front surface inletport 122.

As the indoor unit 10 operates, an upper end or a lower end of the frontpanel 13 may be rotated away from the front frame 12 or may be movedvertically relative to the front frame 12 to allow the front surfaceinlet port 122 to be opened or exposed. A discharge grill 14 may beprovided on a lower end of the indoor unit 10 so that a second end ofthe heat exchanger 16 may be seated on an upper side of the dischargegrill 14. An air outlet port 141 may be formed on a lower side of thedischarge grill 14. A lower end of the stabilizer 112 may extend to theair outlet port 141. A discharge louver 143 that controls a leftward andrightward flow of discharged air and a discharge vane 142 that not onlyselectively opens/closes the air outlet port 141 but also controls anupward and downward flow of the discharged air may each be provided onthe air outlet port 141. The discharge vane 142 and the discharge louver143 may be rotatably coupled to each other on a lower side of thedischarge grill 14. In certain embodiments, the heat exchanger 16 mayhave a shape in which coolant pipes are arranged in 3 rows from front toback or are divided into plural sections so as to surround a front andan upper portion of the fan 17, and the fan 17 may be a cross flow fan.

FIG. 2 is a front perspective view of the chassis shown in FIG. 1. Inthe embodiment shown in FIG. 2, the heat exchanger seating part 111 andthe stabilizer 112 are formed on the front surface of the chassis 11,and a fan supporter 114 is provided at a first end of the chassis 11,along a corresponding end of the stabilizer 112. A motor seating part113 is provided on a side of the fan supporter 114 to support a motorthat drives the fan 17. A fan insertion groove 115 may be formed at asecond end of the chassis 11 opposite the first end. The fan insertiongroove 115 may have a predetermined depth t, or thickness, to supportthe corresponding end of the fan 17.

Fan noise may be generated differently depending on the extent to whichthe fan insertion groove 115 extends into the chassis 11, its thicknessor depth t, and its shape. Therefore, the depth t of the fan insertiongroove 115 may be one design factor to consider for reducing noise ofthe indoor unit 10. Hereinafter, the relationship between the depth t ofthe fan insertion grove 115 and noise, and determination of anappropriate depth t of the fan insertion groove 115 will be explained.

Referring to FIGS. 3 and 4, the fan 17 included with an indoor unit 10as embodied and broadly described herein may be a cross flow fan, andthe cross flow fan may include a plurality of blades 171 that areradially arranged in a circumferential direction. Each blade 171 may beslanted at a predetermined angle θ, such that a line that extends alonga width s (see FIG. 5) direction of each blade is not parallel to arotation shaft of the fan 17, but instead is slanted by thepredetermined angle θ. The fan 17 defines a mean camber line by means ofan inner diameter D1 from a center to an inner end, or root end, of theblade 171, an outer diameter D2 from a center to an outer end, or tipend, of the blade 171, an inner circumferential angle β1 and an outercircumferential angle β2. The mean camber line of the blade 171(hereinafter, referred to as a camber line) is a line that bisects athickness T of the blade 171, essentially following the contour of theblade.

The inner circumferential angle β1 is an angle defined by a lineconnecting the inner end, or root end, of the camber line to the centerof the fan 17 and a tangential line that passes through the inner end,or root end, of the camber line at the inner diameter D1. Hereinafter,the inner circumferential angle β1 will be set to approximately 90degrees. The outer circumferential angle β2 is an angle is defined by astraight line that extends outward from the outer end, or tip end, ofthe camber line and a tangential line that passes through the outer end,or tip end, of the camber line at the outer diameter D2.

Referring to FIG. 5, the blade 171 may have a predetermined chord lengthL and a predetermined width s and may be somewhat rounded in the lengthL direction. More specifically, an inner curvature p1 of the blade 171(at a surface of the blade 171 that is oriented toward the center of thefan 17) may be different from an outer curvature p2 thereof (at asurface of the blade 117 that is oriented away from the center of thefan 17). Therefore, a thickness of the edge portion of the blade 171 maybe different from that of the central portion. In other words, the blade171 has a shape that is thick and then becomes thin from one end to theother end. And, the length L of the blade 171 is defined based on astraight line distance from the inner, root, end of the blade 171 to theouter, tip, end thereof.

In an indoor unit 10 in which the fan 17 constituted as described aboveis installed, the relationship between a ratio of inner diameter D1 toouter diameter D2 of the fan 17 and noise, the relationship between anouter circumferential angle β2 and noise, the relationship between aratio of thickness T to length L of a fan and noise, the relationshipbetween a ratio of an insertion depth t of a side end of a fan to alength L of the fan and noise, may all be taken into consideration inreducing fan noise.

FIG. 6 is a graph of the relationship between an outer circumferentialangle β2 and noise in a fan in which an inner circumferential angle β1is set to approximately 90 degrees. As shown in FIG. 6, noise is on adownward trend and continues to be reduced until the outercircumferential angle β2 of the blade 171 reaches approximately 30degrees and then begins to increase as it exceeds 30 degrees. Thus,noise may be minimized when the outer circumferential angle β2 isapproximately 30 degrees. In certain embodiments, the outercircumferential angle β2 of the blade 171 is preferably 28 degrees≦β2≦32degrees, and more preferably, 30 degrees≦β2≈32 degrees.

FIG. 7 is a graph of the relationship between a ratio of inner diameterto outer diameter D1/D2 and noise in a fan of an indoor unit as embodiedand broadly described herein. As shown in FIG. 7, noise is on a downwardtrend and continues to be reduced until the ratio of inner diameter toouter diameter D1/D2 is approximately 0.79 and then increases as theratio of inner diameter D1/D2 to outer diameter exceeds 0.79. In certainembodiments, the ratio of inner diameter to outer diameter of the blade171 is preferably 0.77≦D1/D2≦0.81, and more preferably, 0.77≦D1/D2≦0.8.

FIG. 8 is a graph of the relationship between a ratio of thickness tolength T/L of a fan blade 117 and noise in a fan of an indoor unitaccording to an embodiment as broadly described herein. As shown in FIG.8, noise is on a downward trend and continues to be reduced until theratio of thickness to length T/L reaches approximately 0.1, and thenincreases as the ratio of thickness to length T/L exceeds 0.1. In otherwords, the noise level is minimized at a point where the ratio ofthickness to length T/L is approximately 0.1. In certain embodiments,the ratio of thickness to length of a fan is preferably 0.088≦T/L≦0.132.

FIG. 9 is a graph of a relationship between a ratio of an insertiondepth t to length L and noise in a fan of an indoor unit according to anembodiment as broadly described herein. As shown in FIG. 9, noise is ona downward trend and continues to be reduced until the ratio of aninsertion depth to length t/L reaches approximately 0.007, and thenincreases as the ratio of an insertion depth to length t/L exceeds0.007. In other words, the noise level is minimized at a point where theratio of an insertion depth to length is approximately 0.007. In certainembodiments, the ratio of thickness to length t/L is preferably0.0044≦t/L≦0.0143.

Thus, a blowing function may be improved or maximized in a fan of anindoor unit as embodied and broadly described herein when designed basedon the noise level parameters shown in FIGS. 6 to 9. In particular, theblowing function may be improved and the noise level may be reduced whena fan 17 and its blade 171 have a structure that takes these parametersinto consideration.

FIG. 10 is a graph of noise performance improvement of an indoor unitincluding such a fan. As shown in FIG. 10, noise generated by a fan thatdoes not include the improved structure as described above isrepresented by the lighter, grey portion of the graph, while noisegenerated by a fan including the improved structure as described aboveis represented by the black portion of the graph. A mean, or average,noise difference between these two exemplary fans, i.e., the mean oraverage of the noise level difference between the “before” and “after”lines at measured corresponding points is approximately 2.2. Thus, noisemay be reduced by about 2.2 dB when the structure of the fan is improvedas described above. This allows blowing performance of the fan to beincreased and system resistance and fan noise to be reduced, and may beapplied regardless of the size of the indoor unit and/or the size of thefan.

An indoor unit for an air conditioning apparatus as embodied and broadlydescribed herein may include a chassis including a stabilizer thatgenerates a flow of air, and a fan insertion groove; a cross flow fanthat is mounted on a front surface of the chassis corresponding to anupper end of the stabilizer, to inhale indoor air; a heat exchanger thatis provided on a front side of the fan to perform a heat exchange withthe indoor air, wherein 0.088≦T/L≦0.132 (T: thickness of fan, L: lengthof fan).

In an indoor unit for an air conditioning apparatus as embodied andbroadly described herein, system resistance may be reduced even when a 3row heat exchanger is applied in order to improve heat exchangeefficiency of the indoor unit. Also, although resistance due to dustaccumulated on a heat exchanger or a filter is increased due to extendeduse, the fan may be normally operated without generating abnormal noise.Also, although a 3 row heat exchanger is used, the noise level may bereduced.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, numerous variations andmodifications are possible in the component parts and/or arrangements ofthe subject combination arrangement within the scope of the disclosure,the drawings and the appended claims. In addition to variations andmodifications in the component parts and/or arrangements, alternativeuses will also be apparent to those skilled in the art.

1. An indoor unit for an air conditioning apparatus, comprising: achassis, including: a stabilizer; and a fan insertion groove formed at afirst end of the stabilizer and a fan supporter provided at a second endof the stabilizer; a cross flow fan supported in the chassis by the faninsertion groove and the fan supporter, and extending across a portionof the stabilizer, wherein the fan draws indoor air into the indoor unitand the stabilizer guides the indoor air through the indoor unit; and aheat exchanger provided an inlet side of the cross flow fan so as toperform a heat exchange with the indoor air, wherein a ratio of athickness T of a blade of the fan to a chord length L of the blade ofthe fan is greater than or equal to 0.088 and less than or equal to0.132.
 2. The indoor unit of claim 1, wherein a ratio of an innerdiameter D1 to an outer diameter D2 of the fan is greater than or equalto 0.77 and less than or equal to 0.80.
 3. The indoor unit of claim 1,wherein an outer circumferential angle β2 of the cross flow fan isgreater than or equal to 30 degrees and less than or equal to 32degrees.
 4. The indoor unit of claim 1, wherein a ratio of an insertiondepth t of the fan to the chord length L of the blade is greater than orequal to 0.0044 and less than or equal to 0.0143.
 5. The indoor unit ofclaim 1, further comprising: a front frame coupled to the chassis so asto form an interior space of the indoor unit therebetween, wherein thefan and the heat exchanger are positioned in the interior space; aninlet grill and an inlet port formed in the front frame, each atpositions corresponding to respective portions of the heat exchanger soas to guide indoor air therethrough and into the heat exchanger; a frontpanel movably coupled to the front frame so as to selectively open andclose the inlet port; and a discharge grill coupled to the front frameand positioned so as to define an outlet port together with the chassis.6. The indoor unit of claim 5, wherein the heat exchanger is positionedin the interior space between the inlet grill and the fan, and betweenthe inlet port and the fan, such that rotation of the fan draws indoorair through the inlet grill and the inlet port and through the heatexchanger for heat exchange, and then draws heat exchanged air throughthe fan for discharge from the indoor unit through the outlet port. 7.The indoor unit of claim 5, further comprising: a louver rotatablypositioned between an outlet of the fan and the outlet port, wherein thelouver controls a lateral flow direction of heat exchanged air throughthe outlet port; and a vane rotatably positioned at the outlet port,wherein the vane selectively opens and closes the outlet port andcontrols a vertical flow direction of heat exchanged air through theoutlet port.
 8. The indoor unit of claim 1, wherein the fan includes aplurality of blades each having a predetermined curvature from a rootend to a tip end thereof, and a mean camber line that bisects thethickness T of the blade and follows the predetermined curvature of theblade.
 9. The indoor unit of claim 8, wherein an inner circumferentialangle β1 is formed between a first line that connects a root end of themean camber line and a center of the fan and a second line that extendstangentially through the root end of the blade, and an outercircumferential angle β2 is formed between a third line formed as anextension of the mean camber line from a tip end of the blade and afourth line that extends tangentially through the tip end of the blade.10. The indoor unit of claim 8, wherein the predetermined curvature ofthe blade includes a first predetermined curvature that defines a firstsurface of the blade, and a second predetermined curvature that definesa second surface of the blade opposite the first surface, wherein thefirst predetermined curvature is different from the second predeterminedcurvature such that the thickness T of the blade varies along the chordlength.